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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script>
    // 数字与数字运算
    // console.log(4 + 5);
    // console.log(4 * 5);
    // console.log(4 / 5);
    // console.log(4 % 5);

    // NaN参与
    // console.log(NaN + 5);
    // console.log(NaN * 5);
    // console.log(NaN / 5);
    // console.log(NaN % 5);

    // Infinity
    // console.log(Infinity + 5);
    // console.log(Infinity - 5);
    // console.log(Infinity * 5);
    // console.log(Infinity / 5);
    // console.log(Infinity % 5);
    // console.log(-Infinity + 5);
    // console.log(-Infinity - 5);
    // console.log(-Infinity * 5);
    // console.log(-Infinity / 5);
    // console.log(-Infinity % 5);
    // console.log(5 / Infinity);
    // console.log(5 % Infinity);
    // console.log(Infinity + Infinity);
    // console.log(Infinity - Infinity);
    // console.log(Infinity * Infinity);
    // console.log(Infinity / Infinity);
    // console.log(Infinity % Infinity);

    // 非正常情况2
    // 字符串参与
    console.log(1 + "2");
    console.log(1 - "2");
    console.log(1 * "2");
    console.log(1 / "2");
    console.log(1 % "2");
    console.log(1 - "");
    console.log(1 - "   ");
    console.log(1 - "12abc");

    // 其他数据类型参与
    console.log(1 + true);
    console.log(1 + false);
    console.log(1 + undefined);
    console.log(1 + null);
  </script>
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